JPS60114548A - Zinc alloy for electrode - Google Patents

Abstract

PURPOSE:To increase the hydrogen overvoltage of an electrode of a primary cell and to prevent the corrosion by adding prescribed percentages of Ga, In and Pb to Zn. CONSTITUTION:This Zn alloy for an electrode contains 0.01-0.5% Ga and 0.01- 0.5% Pb or further contains 0.001-0.01% In. Though the amounts of expensive Ga and In added are small, by adding a little Pb, the hydrogen overvoltage of an electrode of a primary cell made of the Zn alloy is increased, and the corrosion is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gallium-zinc alloy, particularly a gallium-lead alloy.
This relates to an electrode alloy G consisting of a zinc alloy or a gallium-lead-indium-zinc alloy.

- Zinc or zinc alloy used as electrodes for secondary batteries must be free from local corrosion during battery use and storage, deformation of the battery container due to hydrogen gas, and no leakage from the container. ing. Until now, zinc has been frozen in order to maintain these properties of zinc for electrodes, which effectively increases the hydrogen overvoltage of the electrode, suppresses corrosion, and therefore reduces the amount of gas generated. The utilization rate of zinc has also been increased, and the performance of primary batteries has been improved by using mercury, but in recent years, from the perspective of preventing pollution, alternative materials for frozen zinc or icing have been developed. It is also true that improved processing is increasingly desired.

In view of this situation, the present inventors first discovered a mercury-free gallium-zinc alloy as an electrode material that could replace frozen zinc. He focused on indium as a second element in search of alternative materials, and eventually found the cooperative effect range of gallium-indium and was able to provide a zinc alloy for electrodes consisting of gallium-indium-zinc. Showa 58-
No. 26456).

The inventors of the present invention proceeded with research on the descendants, and the
They investigated combinations with second and third elements, including lead, which was suggested to be useful in the invention of No. 26456, and eventually confirmed the cooperative effect of lead-indium-gallium. The cooperative effect of lead and gallium is particularly remarkable, and a small amount of each in combination produces a remarkable effect.
O1~o, o o i% gallium-indium-
Compared to the case of zinc alloy, it has been found that the amount of gas generated is small even with a smaller amount of indium, and furthermore, the amount of gas generated is small even without indium, so that it can be put to practical use.

That is, 9 the present invention uses gallium 0. Zinc alloy containing 0.01 to 0.5% Ol and 0.01 to 0.5% lead, and 0.01 to 0.5% gallium, 0.01 to 0 lead
, 5% and 0.001 to 0.01% indium.

The present invention will be explained by way of examples thereof.

Practical 4 made by a spraying method with varying lead and gallium contents.
II (lead alloy powder (lead alloy powder) whose particle size was adjusted to 8 to 150 mesh
In the method of JP-A-58-26455 and JP-A-58-26456, the gas generation rate was determined in order to examine the battery characteristics for cells (less than 200 meshes).

The gas generation rate was determined by immersing 5.0 g of test zinc alloy powder in a 35% potassium hydroxide aqueous solution at 45° C. saturated with zinc oxide, and determining the amount of gas generated over 3 days.

0.005% gallium for each lead content of 0.005%, 0.01%, 0.05%, 0.1% and 0.5%.
0. Ol.

Gas generation rate (ttL/
g/day) were as shown in Table 1.

Table 1 shows that the gas generation rate of 3 μtag/day or less obtained with zinc boride powder with a mercury concentration of about 5% or more, which is currently in practical use, is at least 0.01% lead and 0.01% gallium.
It can be seen that the above has been achieved.

Furthermore, the lead content is 0.01.0.05.0.1 and 0.0.
For each 5%, the gallium content is 0.01
, 0.05°0.1, 0.25 and 0.5%, and then two of each again to reduce the indium content to 0.
．． 001.0.005゜0.01, 0.05 and 0
．． Tables 2 to 5 show the results of gas generation rates for lead-gallium-indium-zinc alloys with a concentration of 1%.

As shown in Table 2, Table 3, and Table 4, the amount of gas generated tends to decrease as the amount of lead added7 or the amount of gallium increases, but under the coexistence of lead and gallium, So what is the optimal content range for indium?

It tends to be significantly lower than when no lead is added, and 0
．． It was found that the effect was significant at 0.01% or less.

The reason for such a combined effect of lead, gallium, and indium is not clear at present, but it is thought that they suppress the effects of other iron ring impurities.

A large amount of lead reduces the amount of zinc as a battery active material, which reduces the actual power generation and consumption (this is disadvantageous, makes alloy manufacturing difficult, and may also lead to pitting). 9 In the present invention, the first limit is 0.5%, which was confirmed to be effective in the above example, and the lower limit is 0.0% based on the above results.
It was set at 1%.

Galiut is definitely effective as mentioned above.
The lower limit was set at 1%. The upper limit is considered to be preferably 0.5% due to the high cost and alloying considerations, but this does not preclude the use of higher amounts depending on the situation.

As for indium, it can withstand practical G sufficiently even without addition, as seen in the example of the lead-gallium-zinc alloy, but a more suitable effect can be obtained by adding it in the range of o, ooi% or less. It is something that can be done.

For the above alloys, the zinc utilization rate expressed as the ratio of the actual discharge capacity to the theoretical discharge capacity was the same as in the case of conventional frozen zinc, and there was no problem.

Note that the electrode material of the present invention is an alloy material, and unlike zinc powder deposited by displacement from a simple gallium salt or indium salt solution, the gas generation rate remains uniform and the zinc utilization rate is also effective. be.

As described above, the present invention achieves the following by adding a small amount of inexpensive lead.
While suppressing the amount of expensive gallium and indium added, it maintains advanced battery characteristics that cannot be seen when these metal elements are added alone to zinc, and is extremely practical as it is ice-free. It is a zinc alloy for electrodes with high

Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of the case: Japanese Patent Application No. 58-2207322, Title of the invention: Zinc alloy for electrodes 3, Relationship with the person making the amendment: Address of the patent applicant: Nippon', Chuo-ku, Tokyo M3-chome 12-2 Name: Toho Zinc Co., Ltd. 4, Agent 6, Subject of amendment: Akira # 7, Contents of amendment: The size of the typeface in the specification of the application was smaller than "Type 14", so it was retyped. I will submit the certificate as attached.

Claims (2)

[Claims] (1) Gallium 0.01 to 0.5% and lead 0.0
A zinc alloy for electrodes, characterized in that the zinc alloy contains 1 to 0.5% of zinc. (2) Gallium 0.01 to 0.5%, Indium 0
．． Lo, 0.01% and lead 0.01 to 0.001%.
A zinc alloy for electrodes, characterized in that it consists of a zinc alloy containing 5%.